When James Howe built the first rifles and ammo for the 400 Whelen that him and Col. Whelen came up with James use cylindrical 30-06 brass (brass that had not been formed or necked). He used a shoulder of .458 not .441 of the 30-06. The Griffin & Howe built rifles for it in the 1920's and'30's, they were cambered this way and work perfect. Elmer Keith had a Griffin & Howe 400 W and He had good success with it. Some how this info was not let out or was over looked and many gunsmiths made rifles with the .441 shoulder and had bad headspace with it, so it was labeled and bad cartridge by them and many who never used it or researched it. Michael Petrov did a lot of research and found the truth. He even got to use Col. Whelens reloading dies, and one of his rifles if I remember right. I got some loading help from two grate guys I found on the 24hourcampfire forum. One lives in Alaska and he and his wife have used it on caribou and moose. The other guy is in Oklahoma and has use it in Africa on game up to and including cape buffalo.I saw the 400 whelen in PO Ackleys old books. How can you maintain headspace with that?